Mechanical Engineering

Hydraulic Launched Roller Coaster: What Went Wrong?

Hydraulic launches, their problems, and how they compare to other launches

Description 0-72 mph in 2 seconds, about 4.2G. Date 10 August 2013, 12:35 Source Storm Runner hydraulic launcher Uploaded by clusternote Author Paulo Ordoveza from Washington, DC

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By: Jason Reznikov, Journalist

What Are They?

A hydraulic launch is a type of launch mechanism used on launched roller coasters. It is one of many launch mechanisms, which include magnetic launches, compressed air launches, and drive tire launches. Hydraulic launches are a very complex method of launching. First, a catch car, called a sled, attaches to the underside of a roller coaster train. In the center of the long launch track lies a cable that winds up on a drum located at the start of the launch trach. The hydraulic system powers the drum, which starts spinning extremely quickly. This causes the sled, which is attached to the cable, to pull the train at incredible speeds.

How Do They Compare to Other Launches?

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When they were introduced, hydraulic launches could produce the fastest accelerating launches, meaning that they could accelerate to speeds in a much shorter amount of time then the other methods available at the time. These methods were drive tire launches, compressed air launches, and magnetic launches. Magnetic launches are split in two categories: LIMs and LSMs. LSMs came first, and are significantly more unreliable and inefficient than LIMs, which are the current standard for launches. Over the last 20 years of technological evolution, LIMs have become almost as powerful as hydraulic launches while also being both cheaper and more reliable. Drive tire launches are the original launches, first introduced in 1982. Drive tire launches are no longer utilized on large coasters due to their relatively slow acceleration, but they are still commonly used on family coasters, as they are cheap and reliable. Air compressed launches were introduced in 2001 as the most powerful launch, being able to accelerate trains even faster than hydraulic launches. These launches function similarly to hydraulic launches, but they use compressed air instead of hydraulics. They are not commonly used, however, due their unreliability. Hydraulic launches are also incredibly unreliable and expensive, breaking down constantly and needing constant maintenance.

The Problem with Hydraulic Launches

Hydraulic launches, as powerful as they are, have many problems. On the launch track, there are hundreds of brake fins that are put in place, in case the train rolls back onto the launch track. However, the train cannot launch if these brake fins are in position. Because of this, there is a mechanism that lowers the brake fins when the coaster launches and raises them when the train leaves the launch track. Each of these fins have a sensor to make sure

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that they are in the proper position. If any of these sensors detects the smallest issue, even if there is no real problem, the entire ride will shut down. This increases wait times as riders have to wait for the ride to reopen before getting in line. Another major problem with these coasters is the constant maintenance that they require. If the do not receive this maintenance, they could risk the launch cable snapping off and hurting riders. This happened once before in 2009 when a kid riding Xcelerator at Knott’s Berry Farm got seriously injured after the launch cable snapped and cut through the center of the train. Hydraulic launch coasters seem to be at their end, however, as many of these rides are either closing or receiving massive renovations to replace the launch track with an LSM launch system.